DE69123228T2 - Process for producing a chemically adsorbed layer - Google Patents

Description

This invention relates to a method for producing a chemically adsorbed film. In particular, the invention relates to a method for efficiently forming a chemically adsorbed monomolecular film and/or polymer film as a surface film. The method can be applied in the production of e.g. glass, metals, ceramics, plastics and semiconductors.

In the manufacture of, for example, glass, metals, ceramics, plastics and semiconductors, water-repellent, oil-repellent, anti-fogging and stain-resistant properties as well as durability and various other properties are imparted to the manufactured substrates by applying a coating film on the substrate surface. By imparting these properties, the value of the manufactured products can be increased.

Known methods for applying a coating film to a substrate surface include dipping, spraying, brushing, spin coating, and printing methods such as planographic printing, letterpress printing, and screen printing. However, in these methods, the coating solution is only physically applied to the substrate surface, and the adhesion between the substrate surface and the coating film is not sufficiently high. The coating film should have a specific thickness. However, it is difficult to form a coating film with a thickness in the nanometer range, which is uniform, and which has no pores, using the known methods.

The inventors have proposed a method for producing an adsorbed film using a chemical adsorption method. In this method, a substrate with hydrophilic groups on the surface are immersed in and held in an organic solution containing molecules with terminal functional molecular groups (hereinafter referred to as "material to be chemically adsorbed") which can react with the hydrophilic groups. The adsorption reaction is carried out at a constant temperature and at rest or with movement. Without being bound to a particular theory, it is assumed that the reaction between the hydrophilic groups on the substrate surface and the material to be chemically adsorbed proceeds very quickly so that an adsorbed film is formed.

However, it was found that the previously proposed method for producing a chemically adsorbed film had problems. That is, when the reactivity between the material to be chemically adsorbed and the hydrophilic groups on the substrate surface was low, or when there were bulky functional groups or side chains in the material to be chemically adsorbed, the material could not sufficiently approach the substrate due to reduced reactivity or due to steric effects. Consequently, a long time was required to form a high-density chemically adsorbed film (i.e., a dense film). In addition, a decrease in the concentration of the material to be chemically adsorbed during the course of the treatment resulted in reduced adsorption and thus in a low density of the chemically adsorbed film.

Even if the reactivity between the chemically adsorbed material and the hydrophilic groups located on the substrate surface was high, the rate of adsorption was greatly reduced in the last phase of adsorption. This was due to the apparent decrease of the hydrophilic groups, such as hydroxyl groups (commonly referred to as "active sites for adsorption"), on the substrate due to the interaction between the unreacted hydrophilic groups and the chemically adsorbed material. Material that formed a barrier during the adsorption process.

The present invention improves the method for producing the chemically adsorbed film that has been previously proposed, and provides a method for producing a high-density chemically adsorbed film that can be carried out in a short time.

An object of this invention is to provide a method for producing a chemically adsorbed monomolecular film on the surface of a substrate, the surface containing active hydrogen groups, the method comprising:

(A) preparing a solution of a material to be chemically adsorbed by dissolving a material to be chemically adsorbed in a non-aqueous organic solvent, the material to be chemically adsorbed having terminal functional molecular groups which can react with the active hydrogen groups on the substrate surface,

(B) immersing the substrate in the solution of the material to be chemically adsorbed and applying ultrasonic waves to adsorb the material to be chemically adsorbed onto the substrate surface, and

(C) flushing away the unreacted chemically adsorbed material from the substrate surface using a non-aqueous organic solution.

It is preferred in this invention that the ultrasonic waves are applied to the organic solution when the unreacted material to be chemically adsorbed is flushed away (i.e. in step C).

Another object of this invention is to provide a process for producing a chemically adsorbed polymer film on the surface of a substrate, the surface of the substrate containing active hydrogen groups, the process comprising:

(a) preparing a solution of a material to be chemically adsorbed by dissolving a material to be chemically adsorbed in a non-aqueous organic solvent, the material to be chemically adsorbed having terminal functional molecular groups that can react with the active hydrogen groups on the substrate surface,

(b) immersing the substrate in the solution of the material to be chemically adsorbed and applying ultrasonic waves to adsorb the material to be chemically adsorbed on the substrate surface,

(c) forming an adsorbed precursor film on the substrate by reacting the terminal functional molecular groups after immersion with water, and

(d) drying the adsorbed precursor film.

It is preferred in this invention that the molecular terminals of the material to be chemically adsorbed comprise at least one group selected from a halogenated silyl group (-SiX), a halogenated titanyl group (-TiX), a halogenated stannyl group (-SnX), a lower alkoxysilyl group (-SnOR), a lower alkoxytitanyl group (-TnOR) and a lower alkoxystannyl group (-SnOR), wherein X represents chlorine, bromine, fluorine or iodine, and R represents a C1-C6 alkyl group.

It is preferred in this invention that the material to be chemically adsorbed comprises a terminal functional chlorosilyl group (-SiCl) and a fluorine group.

It is preferred in this invention that the concentration of the material to be chemically adsorbed in the non-aqueous organic solvent is in the range of 10⁻⁴ to 10⁻¹ moles per liter.

It is preferred in this invention that the substrate comprises a material selected from the group consisting of glass, metals, ceramics, plastics and semiconductors.

It is preferred in this invention that the substrate is an oxidatively treated plastic substrate.

According to the invention, a chemically adsorbed monomolecular film and/or polymer film with high density can be formed more efficiently on the substrate surface. This is achieved by step B among steps A to C, wherein the use of ultrasonic waves increases the probability of reaction of the material to be chemically adsorbed with active hydrogen groups such as hydroxyl groups or imino groups present on the substrate surface. In addition, the probability of reaction of unreacted active hydrogen groups still present on the substrate can be increased by causing already adsorbed single molecules to vibrate. Using the chemical adsorption method according to the invention, a uniform hydrophobic film with a thickness in the nm range can be formed on the surface of a substrate without impairing the gloss and transparency of the substrate. In this way, it is possible to provide a substrate that is extremely hydrophobic, oil-repellent, substantially non-porous, heat-resistant, durable and dirt-repellent. In the subsequent step C, the unreacted material to be chemically adsorbed is adsorbed using a non-aqueous organic solution. In this way, a monomolecular film with a uniform thickness can be obtained in a short time.

Furthermore, in step C, in a preferred embodiment of the invention, ultrasonic waves are also supplied to the organic solvent so that unreacted material to be chemically adsorbed can be efficiently washed away.

Furthermore, if the frequency of the ultrasonic waves in step B is in a range of 1 to 1000 kHz, preferably in a range of 25 to 50 kHz, the material to be chemically adsorbed can be brought into contact with the substrate surface efficiently so that the reaction can proceed. The above ranges also apply to step C, in which the material to be chemically adsorbed can be efficiently washed away.

According to the second aspect of the invention (the method comprising steps (a) to (d)), a chemically adsorbed polymer film is formed on the substrate.

The chemically adsorbing material that can be used is a compound in which a molecular terminal comprises at least one group selected from the group consisting of a halogenated silyl group (-SiX), a halogenated titanyl group (-TiX), a halogenated stannyl group (-SnX), a lower alkoxysilyl group (-SiOR), a lower alkoxytitanyl group (-TiOR) and a lower alkoxystannyl group (-SnOR), wherein X represents Cl, Br, F or I, and R represents a C1-C6 alkyl group. In order to impart water-repellent, oil-repellent, anti-fogging and anti-staining properties, durability and various other properties to the substrate, the chemically adsorbing material that can be used is preferably a compound having a chlorosilyl group (-SiCl) at one molecular terminal and a fluorine group at another molecular terminal. Furthermore, if the material to be chemically adsorbed contains conjugated unsaturated bonds, the individual chemically adsorbed molecules can be polymerized to form conjugated unsaturated bonds, so that it is possible to form a monomolecular film with various properties, such as electrical conductivity.

According to the invention, the concentration of the material to be chemically adsorbed in the non-aqueous organic solvent is preferably in the range of 10-4 to 10-1 mol per liter. In this concentration range, a monomolecular film and/or a polymer film can be efficiently formed.

According to the invention, the substrate can consist of any material. However, the material is preferably selected from glass, metals, ceramics, plastics and semiconductors. Furthermore, according to the invention, it is preferred to use plastic substrates whose surface has been oxidatively treated.

Fig. 1 is a diagram showing the end of an adsorption process in an embodiment of the invention;

Fig. 2 is a diagram showing an adsorption solution in an embodiment of the invention;

Fig. 3 is a diagram showing an adsorption process in an embodiment of the invention; and

Fig. 4 is a graph showing the relationship between the adsorption time and the adsorption intensity (amount of adsorption) in an embodiment of the invention.

The principle of producing the chemically adsorbed film according to the invention is based on the formation of a monomolecular film and/or a polymer film by utilizing the reaction between an active hydrogen group, such as a hydroxyl group (-OH), an amino group (-NH₂) or an imino group (=NH) on the substrate surface and a functional group such as a chlorosilyl group at one end of the molecule to be adsorbed. The rate of formation of the adsorbed film and the saturation adsorption of the film molecules are greatly influenced by, for example, the concentration of the adsorbed material, the temperature at adsorption, the rate of reaction between the substrate surface and the molecules to be adsorbed, the shape of the molecules to be adsorbed, the number of hydroxyl groups on the substrate surface and the state of the substrate surface.

Since the chemically adsorbed film produced according to the invention is formed from molecules having functional groups that can react with active hydrogen groups, the atmosphere in which the adsorbed film is formed should have a relative humidity that is as low as possible. Preferably, the adsorbed film is formed in an atmosphere without moisture or in a dry atmosphere.

The frequency of the ultrasonic waves used according to the invention is a frequency capable of causing cavitation. A frequency in the range of 25 to 50 kHz can be used using commercially available ultrasonic rinsing tanks. There is no limitation on the shape of the ultrasonic source as long as the ultrasonic waves can be supplied to a solution containing a material to be chemically adsorbed and in which a substrate is immersed and held.

There is no limitation on the substrate used in the process according to the invention as long as its surface contains active hydrogen groups such as -OH, -COOH, -NH₂ or -NH groups. Examples of substrate materials include various types of glasses such as Quartz glass, fluoride glass and metallic glass, metals such as aluminum, iron, stainless steel and titanium, semiconductors such as silicon and germanium, and plastics such as polypropylene, polystyrene, polyethylene and acrylic resins. Substrates with few hydrophilic groups on the surface, such as plastic substrates, can be prepared for use in the present invention by increasing the number of hydrophilic groups by means of ordinary chemical treatments, eg oxidation with ozone/electron beams. Polyimide resins and polyurethane resins have imino groups (=NH) on the surface and therefore do not need to be pretreated.

An alternative pretreatment for surfaces of substrates, such as glass, metals, ceramics, plastics and silicon dioxide (SiO2), for example, involves depositing a polyhalogenated silane, such as dichlorosilane, trichlorosilane and tetrachlorosilane, on the substrate surface and reacting it with water. The pretreatment can be carried out by rinsing with a non-aqueous solution or by omitting this step, and the pretreatment results in an increase in the number of silanol groups (-SiOH) on the substrate surface. This pretreatment enables the material to be chemically adsorbed to be adsorbed at a high density.

According to the invention, any organic solvent can be used as long as it is a non-aqueous organic solvent, does not attack the substrate and ensures sufficient dissolution of the material to be chemically adsorbed because the material to be chemically adsorbed reacts with water molecules. Examples of organic solvents are solvents based on long-chain alkyl compounds, solvents based on aromatic hydrocarbons, solvents based on aliphatic hydrocarbons and halogen-containing solvents.

The concentration of the solution of the material to be chemically adsorbed can be varied depending on the concentration of the hydrophilic groups present on the substrate surface or the surface of the substrate. If the concentration is too low, the adsorption rate is low. In this case, the application is uneconomical from an industrial point of view, although the process can be carried out on an experimental scale. On the other hand, if the concentration is too high, the number of molecules that can react with the hydrophilic groups on the substrate surface and the adsorption rate are not affected. In addition, the already formed adsorbed monomolecular film can be penetrated to some extent by molecules that can then react with unreacted hydrophilic groups that are still present on the substrate surface in the last phase of adsorption. As a result of this effect, the time required to achieve high saturation adsorption is not significantly affected. Accordingly, it is preferred that the concentration of the solution of the material to be chemically adsorbed is about 10⁻⁴ mol per liter or more, particularly 10⁻³ mol per liter or more. The preferred upper limit is 10⁻¹ mol per liter.

In order to form only a single chemically adsorbed monomolecular film (i.e., not a polymer film) according to the invention, it is necessary to carry out a rinsing process after the formation of the monomolecular film in which unreacted molecules remaining on the monomolecular film are rinsed away without using water. In this rinsing process, the effectiveness of rinsing can be greatly assisted if ultrasonic waves are used. As for the rinsing process, ultrasonic waves can be applied when the substrate is placed in the rinsing solution or while the rinsing solution is being drained via an overflow or when the rinsing solution is renewed several times.

The following are examples of chemically adsorbable materials that are preferably used according to the invention:

CF₃(CH₂)₂Si(CH₃)₂(CH₂)₁₅SiCl₃,

F(CF₂)₄(CH₂)₂Si(CH₃)₂(CH₂)�9SiCl₃,

CF₃CH₂O(CH₂)₁₅SiCl₃,

CF₃COO(CH₂)₁₅SiCl₃,

CF₃(CF₂)�9(CH₂)₂SiCl₃,

CF₃(CF₂)₇(CH₂)₂SiCl₃,

CF₃(CF₂)₅(CF₂)₂SiCl₃,

CF₃(CF₂)₇(CF2)₂SiCl₃ and

CF₃CH₂O(CH₂)₁₅SiCl₃.

As has been shown, according to the invention, ultrasonic waves are used in the formation of the monomolecular film and/or the polymer film. In this way, the adsorption time required to form the adsorbed film can be extremely shortened compared to the known methods. This also applies to industrial mass production. Furthermore, the material to be chemically adsorbed can be adsorbed with a high density using the method according to the invention compared to the known chemically adsorbed films. In this way, it is possible to produce a film that is essentially pore-free (i.e., it has no pores) and to obtain more stable and improved physical and chemical properties of the film. Furthermore, it is possible to improve the orientation of the adsorbed molecules.

According to the invention, a material to be chemically adsorbed is reacted with the active hydrogen groups on a substrate surface by immersing the substrate in a solution of the material to be chemically adsorbed and simultaneously applying ultrasonic waves to the solution. In this way, a monomolecular film and/or a polymer film with a high density that is substantially free of pores can be formed in a short time. That is, while the ultrasonic waves are applied, a material to be chemically adsorbed having a terminal functional group is adsorbed on the substrate surface, thereby forming a chemically adsorbed monomolecular film and/or polymer film. The frequency of the ultrasonic waves is preferably in the range of 25 to 50 kHz. After the formation of the adsorbed film, the substrate can be rinsed to produce a monomolecular film by immersing it in a rinsing solution while applying ultrasonic waves. In this way, unreacted chemically adsorbable material remaining on the substrate can be efficiently flushed away.

The invention is applicable in a wide range of applications.

The invention can be widely applied to the following material surfaces. Surfaces of materials made of, for example, metals, ceramics or plastics, woods and stone materials; these materials can be used, for example, as substrates. The surface of the substrate can also be provided with, for example, paints.

Examples of cutting tools: a kitchen knife, scissors, a knife, a cutting tool, a grater, a razor, hair clippers, a saw, a plane, a chisel, a hand drill, an awl, pliers (cutting tools), a drill bit, the blade of a blender and a juice press, a blade of a grinder, a blade of a lawn mower, a hole punch, a straw cutter, a staple from a stapler, a can opener and a surgical knife.

Examples of needles: an acupuncture needle, a sewing needle, a matting needle, a hypodermic needle, a surgical needle, and a safety pin.

Examples of products of the pottery industry: products made of pottery, glass, ceramic items or enamelled products. For example, sanitary pottery (e.g. a room pot, a wash bowl and a bathtub), tableware (a rice bowl teacup), a bowl (plate), a bowl, a teacup, a glass, a bottle, a coffee pot (siphon), a pan, an earthenware mortar and a cup), vases (e.g. a flower bowl, a flowerpot and a bud vase), water containers (e.g. a breeding tank and an aquarium), chemical experimental equipment (e.g. a beaker, a reaction vessel, a test tube, a flask, a laboratory bowl, a condenser, a stirring rod, a stirrer, a mortar, a plate and a syringe), a roof tile, enamelled tableware, an enamelled wash bowl and an enamelled pan.

Examples of mirrors: a hand mirror, a life-size mirror, a bathroom mirror, a washroom mirror, vehicle mirrors (e.g. a rear-view mirror, a side mirror and a door mirror), half mirrors, street mirrors such as a corner mirror, a shop window in a department store sales room, medical treatment mirrors, a concave mirror and a convex mirror.

Examples of parts of the molding process: molds for pressing, molds for casting, molds for injection molding, molds for compression molding, molds for transfer molding, molds for inflation molding, molds for vacuum molding, molds for blow molding, molds for extrusion molding, molds for fiber spinning and a roller for calendering.

Examples of jewelry: a watch, a gemstone, a pearl, a sapphire, a ruby, an emerald, a garnet, a cat's eye, a diamond, a topaz, a bloodstone, an aquamarine, a turquoise, an agate, marble, an amethyst, a cameo, an opal, a crystal, glass, a ring, a bracelet, a brooch, a tie pin (a pin), an earring, a necklace, jewelry made of platinum, gold, silver, copper, aluminum, titanium, tin and its alloys, stainless steel or a glass frame.

Examples of food molds: cakes, cookies, bread baking, chocolate, jelly, ice cream, ovenware or an ice tray.

Examples of cookware: kitchen utensils (a frying pan and a saucepan), a kettle, a saucepan, a frying pan, a hot plate, a toaster oven and a takoyaki pan (takoyaki plate).

Examples of paper: photogravure paper, water-repellent and oil-repellent paper, poster paper, high-quality airmail paper, wrapping paper, packing paper, drink pack paper, container paper, printing paper and synthetic insulation paper.

Examples of resin(s): a polyolefin such as polypropylene and polyethylene, a polyvinyl chloride resin, a polyamide, a polyimide, a polyamideimide, a polyester, an aromatic polyester, a polycarbonate, a polystyrene, a polysulfide, a polysulfone, a polyethersulfone, a polyphenylene sulfide, a phenolic resin, a furan resin, a urea resin, an epoxy resin, a polyurethane, a silicone resin, an ABS resin, a methacrylate resin, an acrylate resin, a polyacetal, a polyphenylene oxide, a polymethylpentene, a melamine resin, an alkyd resin, and an unsaturated polyester-cured resin.

Examples of rubber materials: styrene-butadiene rubber, butyl rubber, nitrile rubber, chloroprene rubber, polyurethane rubber and silicone rubber.

Examples of electrical household appliances: a television, a radio, a tape recorder, a cassette recorder, a compact disc (CD) player, a refrigerator of a freezer, a deep freezer, an air conditioner, a juicer, a blender, a blade of an electric fan, a lighting device, a rotary dial and a perm dryer.

Examples of sporting goods: skis, fishing rods, pole vaulting poles, boats, yachts, surfboards, golf balls, bowling balls, fishing line, fishing nets and floats.

Examples applicable to vehicle parts:

(1) ABS resin: a lamp guard, a dashboard, trimmer parts, a protective device for a motorcycle

(2) Cellulose plastic: a license plate, a steering wheel

(3) FRP (Fiber Reinforced Plastics): a shock absorber, a machine cover (shell)

(4) Phenolic resin: a brake

(5) Polyacetal: wiper gear, a gas valve

(6) Polyamide: a cooling fan

(7) Polyarylate (polycondensation polymerization with bisphenol A and pseudophthalic acid): a direction indicator lamp or lens, (a cowl board lens), a relay housing

(8) Polybutylene terephthalate (PBT): a rear end, a front bumper

(9) Poly(amino-bismaleimide): engine parts, a transmission housing, a wheel, a chassis suspension

(10) Methacrylate resin: a lamp coating lens, a counter plate and its cover, a center mark

(11) Polypropylene: a shock absorber

(12) Polyphenylene oxide: a radiator grille, a hubcap

(13) Polyurethane: a shock absorber, a bumper, a dashboard, a fan

(14) Unsaturated polyester resin: a car body, a fuel tank, a radiator casing, a meter panel.

Examples of office supplies: a fountain pen, a ballpoint pen, a twist pen (an automatic or a mechanical pen), a pencil case, an envelope, a desk, a chair, a bookshelf, a shelf, a telephone stand, a ruler (for measuring), and a drawing instrument.

Examples of building materials: Materials for a roof, an exterior wall and interiors. Roofing materials such as a brick, a slate and a sheet (a galvanized iron sheet). Exterior wall materials such as wood (including a manufactured wood), mortar, concrete, a ceramic sealant, a metal sealant, a brick, a stone, plastics and metal such as aluminum. Interior materials such as wood (including a manufactured wood), a metal such as aluminum, plastic, paper and fiber.

Examples of building stones: granite, marble and others used for the purpose of building, construction material, architectural fixture, ornament, bath, tombstone, monument, doorpost, stone wall and paving stone.

Examples of musical instruments and sound apparatus: a percussion kit, a string instrument, a keyboard instrument, a woodwind instrument, a brass instrument and others, and a sound apparatus such as a microphone and a speaking device. More specifically, these are musical instruments such as a drum, a cymbal, a violin, a cello, a guitar, a koto (harp), a piano, a flute, a clarinet, a bamboo flute (pan flute) and a horn, sound apparatus such as a microphone, a speaking device and a headphone.

Other examples are a thermos flask, a vacuum bottle and a vacuum vessel.

Examples of a high voltage insulator: e.g. an insulator in power plants/substations or a spark plug, which have strong water-repellent, oil-repellent and dirt-repellent properties.

The invention is described in more detail below using specific examples.

EXAMPLE 1

The process for producing a monomolecular film according to the invention will now be described step by step with reference to Figures 1 to 3.

As shown in Figure 2, a chemically adsorbed material 1 and a non-aqueous organic solvent 2 were placed in a commercially available ultrasonic rinsing tank 3 in dry air, and the chemically adsorbed material 1 was sufficiently dispersed in the organic solvent 2. The organic solvent 2 used here was a mixed solvent (non-aqueous mixed solvent) consisting of 80 wt% of n-hexadecane, 12 wt% of chloroform, and 8 wt% of carbon tetrachloride. The chemically adsorbed material used was nonadecyltrichlorosilane, [CH3(CH2)18SiCl3], which was dissolved at a concentration of 10 mmol per liter.

Then, as shown in Figure 3, a glass substrate 4 was immersed in the solution maintained at a temperature of 30°C. Simultaneously with the immersion, ultrasonic waves were applied. The frequency of the ultrasonic waves was set to 45 kHz, and the high frequency output power was set to 60 W. The glass substrate 4 had sufficient hydroxyl groups on its surface. It was assumed that that monomolecularly adsorbed molecules 5 were present on the substrate 4 as shown in Fig. 3 as a result of the reaction between the material to be chemically adsorbed 1 and the hydroxyl groups on the substrate 4. The monomolecularly adsorbed molecules 5 adsorbed first formed a barrier which hindered the reaction of unreacted chemically adsorbed material 1 with the hydroxyl groups on the substrate, whereby a long time was required to form a high-density chemically adsorbed monomolecular film. In the manufacturing process according to the invention, ultrasonic waves were applied as shown in Fig. 3. The monomolecularly adsorbed molecules 5 adsorbed first were vibrated, thereby promoting the reaction with the hydroxyl groups on the substrate. The dispersion rate of the unreacted chemically adsorbed material 1 was increased, whereby a chemically adsorbed monomolecular film could be formed in an even shorter time.

In this way, hydrogen chloride elimination took place as a result of the reaction between the hydroxyl groups on the substrate surface and the material to be chemically adsorbed 1. Finally, all the hydroxyl groups on the substrate 4 were reacted, thereby forming the monomolecular film. A chemically adsorbed monomolecular film with high density could be formed within a short time.

The chlorosilyl groups (-SiCl) of the fluorine-containing chlorosilane-based chemically adsorbing material and the hydroxyl groups (-OH) on the surface of the glass substrate 4 reacted by hydrogen chloride elimination to form covalent bonds as shown in Equation 1. [Equation 1]

When the surface of the treated glass substrate was exposed to water or when the surface was exposed to atmospheric moisture, chemical bonds were formed as shown in Equation 2. [Equation 2]

Silanol groups (-SiOH) condensed with neighboring silanol groups (-SiOH) to form bonds as shown in Equation 3. [Equation 3]

The chemically adsorbed monomolecular film had a thickness of about 2.1 nm. The wetting angle of the surface of the film with respect to water was measured and found to be about 120º. The monomolecular film was extremely water-repellent, oil-repellent, anti-fogging, anti-staining and durable.

For comparison, a chemically adsorbed monomolecular film was formed in the same manner as in Example 1 described above, except that no ultrasonic waves were applied and the glass substrate was kept still in the nonaqueous solvent.

The adsorption ratio of the adsorbed molecules of the two different chemically adsorbed monomolecular Films on the substrate were evaluated by FTIR. Figure 4 shows the relationship between the adsorption time and the adsorption intensity. The symmetric stretching vibrations of the methylene groups (-CH₂-) and the peak area of the converse symmetric stretching vibrations were calculated from the results of infrared absorption spectral analysis and are given as relative adsorption intensities. As shown in Figure 4, it was confirmed that the adsorption time using ultrasonic waves (marked by the white circles) was only about 1/10 or less of that required without using ultrasonic waves (marked by the black circles). That is, the adsorption rate using ultrasonic waves was at least 10 times higher. In addition, the closer to the saturated adsorption region, the greater the difference between the two. With the method according to the invention, the adsorption density at saturation was increased by about 1.2 times. This shows that the film density was increased.

In order to improve the obtained monomolecular film, the substrate was immersed in chloroform or Freon-113 to rinse it in dry air, and then it was rinsed according to the two methods described above, i.e., once using ultrasonic waves and once without using ultrasonic waves. By using the ultrasonic waves, the substrate could be sufficiently rinsed within 5 minutes, which was about 1/6 of the time required for rinsing without using ultrasonic waves. Thus, the rinsing speed was increased by at least 6 times.

In this case, the frequency of the applied ultrasonic waves was 45 kHz and the high frequency output power was set to 60 W.

If the above mentioned rinsing of the substrate using a non-aqueous organic solution was not carried out, and After rinsing with water and then drying in air, an adsorbed polymer film was formed on the substrate. The adsorbed polymer film was firmly bonded to the substrate, was essentially non-porous, thin, stain-resistant and transparent.

EXAMPLE 2

Under the same conditions as in Example 1, octadecyltrichlorotin was used instead of nonadecyltrichlorosilane as the material to be chemically adsorbed, and the glass substrate was replaced with aluminum. As in Example 1, the formation of the monomolecular film was carried out once using ultrasonic waves and once without using ultrasonic waves, and the results were compared. When the ultrasonic waves were used, the time to saturation could be shortened to 1/5.

In the examples described above, the frequency of the ultrasonic waves was set to 45 kHz and the high frequency output power was set to 60 W. However, the effects of this invention can be achieved using other setting parameters. Using ultrasonic waves generated with commercially available ultrasonic rinse tanks, although the effects varied slightly, the adsorption time or the rinse time could be significantly reduced and the adsorption density could be increased. It is believed that the same effects can be achieved using higher energy ultrasonic waves, provided that the energy is not so high as to damage the substrate. It is also believed that lower energy ultrasonic waves can be used, provided that the energy is high enough to cause the molecules to vibrate.

If the above mentioned rinsing of the substrate using a non-aqueous organic solution was not carried out, and After rinsing with water and then drying in air, an adsorbed polymer film was formed on the substrate. The adsorbed polymer film was firmly bonded to the substrate, was essentially non-porous, thin, stain-resistant and transparent.

EXAMPLE 3

The material to be chemically adsorbed, CF3(CF2)7(CH2)2sicl3, was dissolved in Freon-113 (an organic non-aqueous solvent) at a concentration of 1 x 10 M-2. Into this solution of the material to be chemically adsorbed was placed a substrate consisting of a nylon-6 resin molding. Ultrasonic waves were applied to the solution. The frequency of the ultrasonic waves was set to 45 kHz and the high frequency output power was set to 60 W.

The chlorosilyl groups (-SiCl) of the fluorine-containing chlorosilane-based chemically adsorbing material and the imino groups (=NH) on the surface reacted by hydrogen chloride elimination to form covalent bonds, as shown in Equation 4. [Equation 4]

Unreacted chemically adsorbable material on the surface of the nylon-6 resin molding was removed under Using Freon-113, ultrasonic waves were applied. The frequency of the ultrasonic waves was 45 kHz, and the high frequency output power was set to 60 W. When the surface of the treated nylon 6 resin molding was brought into contact with water or atmospheric moisture, chemical bonds were formed as shown in Equation 5. [Equation 5]

Then, silanol groups (-SiOH) condensed with neighboring silanol groups (-SiOH) to form bonds as shown in Equation 6. [Equation 6]

The chemically adsorbed monomolecular film had a thickness of about 2.1 nm. The contact angle of the surface of the film with respect to water was measured and found to be about 120º. The monomolecular film was extremely water-repellent, oil-repellent, anti-fogging, anti-staining and durable.

When the above-mentioned rinsing of the substrate using a non-aqueous organic solution (Freon-113) was not carried out, and rinsing with water was carried out and then dried in air, an adsorbed fluorocarbon-based polymer film was formed on the substrate. The fluorocarbon-based polymer film was firmly bonded to the substrate, substantially nonporous, thin, stain-resistant and transparent.

As has been shown, the invention is of great industrial importance.

Claims (15)

1. A process for producing a chemically adsorbed monomolecular film on the surface of a substrate, the surface of the substrate containing active hydrogen groups, the process comprising: (A) preparing a solution of a material to be chemically adsorbed by dissolving a material to be chemically adsorbed in a non-aqueous organic solvent, the material to be chemically adsorbed having terminal functional molecular groups which can react with the active hydrogen groups on the substrate surface, (B) immersing the substrate in the solution of the material to be chemically adsorbed and applying ultrasonic waves to adsorb the material to be chemically adsorbed onto the substrate surface, and (C) flushing away the unreacted material to be chemically adsorbed from the substrate surface using a non-aqueous organic solution. 2. A method for producing a chemically adsorbed monomolecular film according to claim 1, wherein the ultrasonic waves are applied to the organic solution while the unreacted material to be chemically adsorbed is washed away. 3. A method for producing a chemically adsorbed monomolecular film according to claim 1 or 2, wherein the frequency of the ultrasonic waves is in the range of 1 to 1000 kHz. 4. A method for producing a chemically adsorbed monomolecular film according to claim 1, wherein the molecular groups of the material to be chemically adsorbed comprise at least one group selected from the group consisting of a halogenated silyl group (-SiX), a halogenated titanyl group (-TiX), a halogenated stannyl group (-SnX), a lower alkoxysilyl group (-SiOR), a lower alkoxytitanyl group (-TiOR) and a lower alkoxystannyl group (-SnOR), wherein X represents chlorine, bromine, fluorine or iodine, and R represents a C1-C6 alkyl group. 5. A method for producing a chemically adsorbed monomolecular film according to claim 1, wherein the material to be chemically adsorbed comprises a terminal functional chlorosilyl group (-SiCl) and a fluorine group. 6. A process for producing a chemically adsorbed monomolecular film according to claim 1, wherein the concentration of the material to be chemically adsorbed in the non-aqueous organic solvent is in the range of 10-4 to 10-1 mol per liter. 7. A method for producing a chemically adsorbed monomolecular film according to claim 1, wherein the substrate comprises a material selected from the group consisting of glass, metals, ceramics, plastics and semiconductors. 8. A method for producing a chemically adsorbed monomolecular film according to claim 1, wherein the substrate is an oxidatively treated plastic substrate. 9. A process for producing a chemically adsorbed polymer film on the surface of a substrate, the surface of the substrate containing active hydrogen groups, the process comprising: (a) preparing a solution of a material to be chemically adsorbed by dissolving a material to be chemically adsorbed in a non-aqueous organic solvent, the material to be chemically adsorbed having terminal functional molecular groups which can react with the active hydrogen groups on the substrate surface, (b) immersing the substrate in the solution of the material to be chemically adsorbed and applying ultrasonic waves to adsorb the material to be chemically adsorbed onto the substrate surface, (c) forming an adsorbed precursor film on the substrate by reacting the terminal functional molecular groups after immersion with water, and (d) drying the adsorbed precursor film. 10. A method for producing a chemically adsorbed polymer film according to claim 9, wherein the frequency of the ultrasonic waves is in the range of 1 to 1000 kHz. 11. A method for producing a chemically adsorbed polymer film according to claim 9, wherein the terminal molecular groups of the material to be chemically adsorbed comprise at least one group selected from the group consisting of a halogenated silyl group (-SiX), a halogenated titanyl group (-TiX), a halogenated stannyl group (-SnX), a lower alkoxysilyl group (-SiOR), a lower alkoxytitanyl group (-TiOR) and a lower alkoxystannyl group (-SnOR), wherein X represents chlorine, bromine, fluorine or iodine, and R represents a C1-C6 alkyl group. 12. A method for producing a chemically adsorbed polymer film according to claim 9, wherein the material to be chemically adsorbed comprises a terminal functional chlorosilyl group (-SiCl) and a fluorine group. 13. A process for producing a chemically adsorbed polymer film according to claim 9, wherein the concentration of the material to be chemically adsorbed in the non-aqueous organic solvent is in the range of 10⁻⁴ to 10⁻¹ moles per liter. 14. A method for producing a chemically adsorbed polymer film according to claim 9, wherein the substrate comprises a material selected from the group consisting of glass, metals, ceramics, plastics and semiconductors. 15. A process for producing a chemically adsorbed polymer film according to claim 9, wherein the substrate is an oxidatively treated plastic substrate.